Process of purifying rubber.



PATENTED MAY 29, 1906.

1 P. G. HOOD. PROCESS OF PURIFYING RUBBER.

APPLICATION FILED MAR. 24, 1905.

3 SHEETS-SHEET 1.

PATENTED MAY 29, 1906.

P. G. HOOD.

PROCESS OF- PURIPYING RUBBER.

APPLIO ATION FILED MAR. 24, 1905.

3 SHEETSSHEET 2.

Wyn/w PATENTED MAY 29, 1906.

F. G. HOOD.

PROCESS OF PURIFYING RUBBER.

APPLIOATION FILED MAR. 24, 1905.

a SHEETS-SHEET s.

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PROCESS OF PURIFIYING RUBBER.

Specification of Letters Patent.

Patented May 29, 1906.

Application filed March .24, 1905. Serial No. 251,824.

To all whom it may concern:

Be it known that I, FREDERro C. H001), a citizen of the United States, residing at Brookline, Massachusetts, have invented certain new and useful Improvements in Processes of Purifying Rubber, of which-the following is a specification.

My invention relates to an improved method of purifying or washing rubber, and

while designed more especially for washing. or purifying crude and reclaimed rubber is sheet of water is allowed to fall upon the.

rubber or other material as it passes between the nip of the rolls. While for the washing of high and medium fair rubbers this arrangement is on the whole considered fairly satisfactory, it has been found entirely inadequate to produce erfectly-washed sheets from earthy niatter, bark, wood, and other vegetable debris, chemical, and all other impurities. This is often due to the fact that the rubber passing through the rolls becomes more or less heated by their mechanical action, and the above-named impurities are caused to adhere to the rubber, and instead of being removedby the next passage of the rubber through these rolls they are ground into the rubber and can no longer be removed from it by this power. It is thus found that all grades of rubber containing material uantities of the above-named impurities at t e end of the washing operation still conties which-has been ground into the ru ber. Particularly in thecase of ve etable impurities their presence in the rub er in a finelycomminuted state is liable to cause blowing in the subsequent vulcanization-in fact, to give rise to quite a number of manufacturing troubles. v

I have found that carrying out the purifying operation 1n such a manner that the rub gutta-percha, and various all those ru bers containing sand,

. another ber sheet is submerged in the washing liquid a great improvement in the purity of the washed sheet is effected, and this improvement is particularly marked in the case of those very impure grades of rubber which at the present time cannot be satisfactorily washed at all. By my improved process and apparatus I also eflect a great saving in time and a material reduction in labor and consequent lessening of cost. r

In carrying out my improved process or method the rolls are immersed in liquid, so that the level of the liquid in the tank rises above the height of the nip of the rolls, and then the rolls are rotated, so that the rubber 'as it passes between the nip of the rolls and at the time it is compressed thereby is flooded in the washing liquid, and the moment it issues from the other side of the rolls it finds itself also submerged, and any impurities which have come to the surface of the rubber sheet are thus at once floated off or deposited at the bottom of the tank, and the sheet itself rises automatically toward the surface of the liquid, where it passes over and is again caught by and carried through the rolls. This operation is continued until the sheet is found to be washed to the requisite state of purity. The dirt and impurities collecting at the bottom of the immersion-tank may be removed periodically or continually carried ofi by means of a pipe leading from the bottom of the tank, while the lighter impurities or those having less specific gravity are floated ofi at the surface of the liquid.

I use the term liquid because while water alone is generally used it may be desirable to add chemicals to the water or to a specific solvent or chemical efiect, and I have shown means for accomplishing this purpose in the drawings.

Some grades of rubber contain impurities which are best removed by the application of warm or hot water, which has a dissolving action thereon, and a further improvement in my process lies in first washing out those impurities which are insoluble by the action of cold water and thereafter raising the temper- ICC ature of the liquid to wash out the soluble impurities either in the same tank-washer or in with it.

I have shown in the 'accompanylng drawings a form of improved apparatus capable of carrying out my improved process.

tank-washer used in conjunction any vent leakage.

In the drawings, Figure 1 is a sectional elevation, the section being taken on line 1 1 of Fig. 2. Fig. 2 is a front view. Fig. 3 is a plan view with the hopper omitted, and Fig 4 1s a sectional detail on line 4 4 of Fig. 1.

In the drawings I have shown at 4 4 a suitable frame in which are journaled the supporting-shafts 5 5 of the rollers 6 and 6, which, as shown, are preferably located side by side. The bearings of one of the rollers '6 are made horizontally adjustable to a limited extent to permit the distance between the rolls to be varied, the adjustment being effected by the screw-bolts 7, having their heads adapted; for the reception of a suitable operatingtoo1.'

The shafts 5 and 5 are provided at one side with intermeshing gears 8 and 8 and one of them is provided at the opposite side of the machine with a large gear-wheel 8 through-which power is imparted to the machine by a gear 8, driven from any suitable source. (Not shown.) The washing-rolls are surrounded by a tank 10, the bottom 10 of which slopes both to the front and to one side, so that all matters washed out by the liquid and which are of greater specific gravity tend to settle, toward one corner of the machine. This corner 10 is connected to an outlet-pipe 1 1, which is provided with a gatevalve 11, by which the outflow of liquid may be regulated or stopped, as desired.

At the upper front side is an extended portion 12, into which the surface liquid flows, carrying with it all impurities, this extended portion having an inclined bottom 13, which communicates at its lower end with a vertical pipe 14, communicating with the pipe 11 above referred to. A vertically-sliding gate or ledge ,15 is provided, which may be raised and lowered by means such as the threaded rods 16 and hand-nuts 17, so that the hei ht of the liquid in the tank may be varied he rods ass through and the nuts 17 bear on the b ocks 17 secured to the flanges 17 of the tank. A screen 18 of suitable mesh is also rovided to revent the ossible loss of fiagments 0 rubber. P ates 6 and 6 are provided, which encircle the shafts of the rolls and are bolted to the side of the tank, so as to holdsuitable packing in place and pre- At 19 inFig. 1 I have shown a tiltin hopper pivotally supported upon suitable rac ets 20, into which the crude rubber to be washed is thrown by the attendant, this hopper'being omitted from Figs. 2 and 3 in order to show other parts. I

' Ordinarily the pan rests in the position shown in readiness to receive the crude rubber, and means a'reprovided by which the attendant may tilt it from the front of the machine when the batch of washed rubber has been removed and a fresh lot of unwashed rubberisto be supplied. A convenif g scribed.

ient form of means for this purpose consists of a chain or like device 23, connected with the rear end of the hopper and passing over pulleys 22 to the front, where it is provided with a pull or handle 24.

When a fresh charge of rubber is dumped upon the rollers, it is carried through between them in a crinkled or irregular sheet. An inclined screen 25, usually assisted by the flow of water toward the outlets, deflects this toward the front of the tank, where, owing to its lightness, it at once rises to the surface of the liquid. Inorder to insure the front edge of this strip, film, or sheet being automatically returned over the nip of the rollers, so as to be again drawn down between the same, I provide apaddle-wheel 26, having its supportingshaft removably journaled in bearing-boxes 27. If this paddle-wheel be rotated by any suitable means in the direction of the arrow, the sheet or film of rubber will be seized by the bladesof the paddle-wheel and be carried back onto the top of the adj oinin roller and thence down between the rolls wit out necessitating the handling of the rubber by the workman at this time.

The washing liquid is preferably supplied to the machine by a horizontal pipe 28, having delivery-openings in its under side. This pipe 28 is located, preferably, directly over the meeting line or nip of the rolls. A Watersupply .pipe 29 connects with this pipe 28by a horizontal pipe 29*, while a steam-su ply pipe 30 connects with the pipe 29, by w oh the temperature of the water may be varied as desired. A ipe 31 also connects with the pipe 29, by which chemicals may be mingled w1th the water when desired. Pipes 30 and 31 are shown only Fig. 2 and omitted from 1 and 3 for convenience. I

'I may find it desirable to provide additional means for varyinguthe temperature of w the washing liquid, in ch event I provide a pipe-coil 32 in the bottom of the tank with branch pipe connections 33 and 34 to the vertical portlon 32 for refrigerating fluid and steam, respectively, with suitable controllingcocks, whereby the body of water in the tank may be directly acted upon. Branch pipes 33 and 34 are for convemence shown only in Fig. 1% A pipe 35 may beprovided for extra water.

Having thus described my invention, what I Claim'is- 1. The herein-described process of purifying rubber and the like which consists in compressing or shredding it between coacting rolls and passin it through a bodyof purifyin liquid Where y the liquid has access to all "si es of the material permitting the heavier 1purities to fall through the liquid and the ter impurities to rise, substantially as de 2. The herein-described rocess of purifying rubber and the like wh'ic 1 consists in com- IIO 4. The herein-described rocess of purifying rubber and the like whic consists in passing it between coacting rolls while submerged in a current of purifying liquid, and utilizing said current to return the rubber issuing from the rolls to the nip of the rolls for a fresh pass, substantially as described.

In testimony whereof I aflix my signature in presence of two witnesses.

' FREDERIC O. HOOD.

Witnesses:

CLINTON. F. FISHER, HERBERT C. MASON. 

